HOMEBREW Digest #5113 Sun 24 December 2006

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  Re: fermentation temp ("Michael O'Donnell")
  re: fermentation temp. (3rbecks)
  Controlling Fermentation Refrigerator Temperature - Part 1 (Fred L Johnson)
  Controlling Fermentation Refrigerator Temperature - Part 2 (Fred L Johnson)
  Don't know where to buy pills? ("Advertise I. Spirally")
  Three Philosphers ("David Craft")

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---------------------------------------------------------------------- Date: Fri, 22 Dec 2006 22:06:01 -0800 From: "Michael O'Donnell" <odonnell at msi.ucsb.edu> Subject: Re: fermentation temp Jeff is wondering about putting a temp probe in the wort... I've never done this, but instead, I take my temp probe, place it against the side of my fermenter (a corny keg) put a piece of neoprene foam on the outside of it and duct tape it in place. I haven't done enough experimenting to see whether this keeps the temp close to the wort, but when I do the same thing on my serving fridge, I definitely get less frequent compressor action, and the temp seems to swing more slowly. Incidentally, since this is one of the rare days when a bunch of spam slipped through the cracks, I'd like to take the chance to raise a glass to Pat and the other janitors for the fantastic job they do keeping this list up, running and mostly spam-free. You guys are great, thanks! moose o'donnell santa barbara, CA Return to table of contents
Date: Sat, 23 Dec 2006 06:42:09 -0600 From: <3rbecks at sbcglobal.net> Subject: re: fermentation temp. Jeff, I use exactly that type of set up. B3 (I believe) has a 2 hole stopper that has a stainless thermowell attached to one of the holes that is about 18 inches long. I run the Ranco probe in the thermowell and control the refrigerator from the actual wort temperature. I set the temperature differential at 1 degree. About the only draw back to this set up is that when the wort temperature rises above the set point (usually during the early stages of fermentation), the refrigerator will run hard for a while and it will overshoot the set point by a degree or two. It's due to the thermal mass of the 6 gallons of wort, I suppose. At the beginning of fermentation, I usually try to chill the wort below the set point because I've found that if I leave it three or four degrees above the set point that the over shoot is much greater. This method is not perfect, but I feel that it's more accurate than my previous method of controlling the temperature by regulating the air temperature inside the refrigerator. I felt that the old way involved too much guesswork, as I didn't really know the actual temperature of the fermenting wort. Rob Beck Kansas City Listening to someone who brews his own beer is like listening to a religious fanatic talk about the day he saw the light. - Ross Murray, Montreal Gazette, 1991 Return to table of contents
Date: Sat, 23 Dec 2006 09:28:49 -0500 From: Fred L Johnson <FLJohnson52 at nc.rr.com> Subject: Controlling Fermentation Refrigerator Temperature - Part 1 There has been some discussion recently regarding where would be the best location to place the temperature probe when regulating the temperature of a refrigerator for fermenting. Some have suggested to control the air temperature of the refrigerator, some have suggested the wort itself by using a thermowell in the fermentor, others recommend putting the probe on the surface of the fermentor and have indicated that this would not work well on plastic because of its poor conductivity. Some has suggested controlling the air temperature but setting it to some temperature lower than the target fermenation temperature to compensate for heat that is generated during the fermentation. I would like to consider these various methods and would like to hear other's thoughts on this. The following are mine. All of the following assumes that the ambient air temperature outside the refrigerator is considerably warmer than the target fermentation temperature. Let's first consider using a thermowell in the wort to regulate the refrigerator. For example, we wish to ferment at 67 F and have precooled the refrigerator to 67 F, but the wort is currently at 70 F. The refrigerator immediately will begin cooling the chamber and will continue until the wort reaches 67 F, which may take significant time, depending upon the volume (mass) of the wort. The chamber could cool to a very low temperature by the time the wort reaches 67 F. The wort will then continue to cool well below the set point because the chamber temperature is so low. The chamber will begin to warm at a rate that depends upon the effectiveness of the refrigerator's insulation, and the wort temperature will continue to decrease below the set point until the air and wort reach the same temperature. The refrigerator will continue to warm and will not turn on again until the wort warms up to the switch-on point (e.g., 2 degrees above the set point). As occurred during the cooling phase, the thermal mass of the wort will cause the wort temperature to lag behind the chamber temperature. When the wort temperature rises to the switch-on point, the chamber temperature will be somewhat higher than the wort temperature. The refrigerator will then begin cooling, and the on/off cycling of the refrigerator will continue, with wort and chamber temperature swings getting progressively smaller with each cycle until the temperature swing is within the differential of the swith-on/swith-off points. End of part 1. Fred L Johnson Apex, North Carolina, USA Return to table of contents
Date: Sat, 23 Dec 2006 09:28:57 -0500 From: Fred L Johnson <FJohnson54 at nc.rr.com> Subject: Controlling Fermentation Refrigerator Temperature - Part 2 Let's now consider placing the temperature controlling probe in the air within the refrigerator chamber. As before, we've preconditioned the chamber to be at the target fermentation temperature of 67 F, and the wort is currently 70 F. When the wort first goes in the refrigerator, the refrigerator may not come on at all or only very briefly because the air temperature wouldn't change much. The wort will gradually cool to the set temperature, and the refrigerator will cycle on and off at about the same rate as it did just before the wort was initially introduced. The chamber temperature will fluctuate little, e.g., +/- 2 F (depending upon the differential that is set), compared to the example when the probe was monitoring wort temperature. Neither of these two examples have included the effect of heat generated by the fermentation, so let's consider that now. The problem is created when the heat generated in the wort is not instantly transferred to the air surrounding the fermentor. In the thermowell scenario, when heat begins to accumulate in the wort, the refrigerator will begin cooling, and this will occur sooner than in the case when the probe is monitoring the chamber temperature. Having the probe in the wort will more effectively minimize the rise in wort temperature. However, at the time the refrigerator turns off, the chamber temperature will again be much cooler than the wort temperature, and the wort will tend to cool further, perhaps well below the set point. The heat of the fermentation will work against this and will minimize the degree to which the wort will chill. The entire problem at hand is the result of non-instantaneous transfer of heat between the wort and the chamber. The better the conduction of heat between the two, the less will be the differential between the two in either scenario. Stirring the wort during fermentation would also help conceivably. It seems to me that the best way to minimize temperature fluctuations of the wort would be to: 1) use a very highly conducting fermentor--stainless steel would be the best among the fermentors that are commonly available (glass, plastic, steel), but silver would be the Cadillac. ;-) 2) pitch only when the wort is at the target fermentation temperature, and 3) control chamber temperature, with the initial setting at the target fermentation temperature, but continually lower the set point over time during fermentation to offset heat generated by the wort and then continually raise the set point over time as the rate of heat generation decreases until the target fermentation temperature is reached. One would need to empirically determine how fast to lower the chamber set temperature during active fermentation and thereafter how fast to raise it as fermentation subsides. This would have to be done by monitoring both the wort and chamber temperatures continually and by experimentally (trial-and-error) changing the chamber temperature set point throughout fermentation. Comments and counter points are encouraged! Is there anyone out there with a couple of YSI temperature controllers and a spare computer to collect the data in my neighborhood? This would be a fun and pretty easy experiment. Fred L Johnson Apex, North Carolina, USA Return to table of contents
Date: Sun, 24 Dec 2006 06:20:12 -0500 From: "Advertise I. Spirally" <extradino at graz.homeip.net> Subject: Don't know where to buy pills? Most wanted pills at LOW price! http://telsiber.com/ any pill you need! Absolutely Confidential and Secure purchase Return to table of contents
Date: Sun, 24 Dec 2006 12:42:33 -0500 From: "David Craft" <Chsyhkr at bellsouth.net> Subject: Three Philosphers Greetings, On this Christmas Eve I am looking for Three Wise Men to help me conjure up some Three Philosphers Ale. I have made sour beers, cherry beers, and Belgian Strong Dark Ale, but am wondering what best brings all this together into this wonderful beer?? Thoughts? David Craft Battleground Brewers Guild Greensboro, NC Return to table of contents
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